Pertussis is still among the principal causes of death world-wide, and its incidence is increasing even in countries with high vaccine coverage. Although all age groups are susceptible, it is most severe in infants too young to be protected by currently available vaccines.
Whooping cough or pertussis is a severe childhood disease responsible for high mortality rates before the introduction of effective vaccines in the second half of the 20th century. The success of these vaccines has led to the opinion that the disease is essentially under control, although world-wide 200,000 to 400,000 pertussis-linked deaths are still recorded annually, and the disease still ranks sixth among the causes of mortality due to infectious agents [1]. Although mostly prevalent in developing countries, the disease is also re-emerging in the developed world [2,3], including the U.S.A., where the incidence has increased five-fold over the last twenty years [4]. Unexpectedly, the epidemiology of pertussis has changed in countries with high vaccine coverage, where cases of adolescent and adult pertussis are increasingly frequent [5]. This is probably due to progressive waning of vaccine-mediated immunity during adolescence. Often atypical and therefore difficult to diagnose, pertussis is generally not life-threatening in adults and in many cases remains unnoticed. However, infected adults constitute an important reservoir for transmission of the disease to very young children, too young to be fully vaccinated, and therefore at risk to develop severe disease associated with high mortality rates.
Pertussis vaccination usually begins at two months of age, and full protection requires at least three immunizations at one- to two-month intervals. Therefore, infants are not fully protected before the age of 6 months using the currently available vaccines. To reduce the incidence of pertussis in the very young and most vulnerable age groups, early immunization, possibly at birth, would thus be highly desirable. However, numerous studies in humans and in animal models have suggested that the neonatal immune system is too immature to effectively induce vaccine-mediated protective immunity [6, 7]. Especially the IFN-γ production, indicative of a Th1 response that is essential to the development of protective immunity to pertussis [8], appears to be significantly reduced in human newborns, compared to older children or adults [9]. This is also reflected by the fact that significant amounts of antigen-specific IFN-γ are only produced after several months (≧6 months) in children vaccinated with pertussis vaccines, especially with acellular vaccines (aPV) [10].
Natural infection with Bordetella pertussis has long been considered to induce strong and long-lasting immunity, that wanes much later than vaccine-induced immunity [5, 11]. Furthermore, infection with B. pertussis induces measurable antigen-specific Th1 type immune responses even in very young children (as young as one month of age) [12]. These observations suggest that live vaccines applicable by the nasal route in order to mimic as closely as possible natural infection, may be attractive alternatives over the currently available vaccines.
There are many vaccinating compositions to treat Bordetella infections known in the art. However, these immunogenic compositions are not used to treat newborn children or in cases where an epidemic and rapid protective immunity is required.
Thus, French Patent FR 0206666 discloses live Bordetella strains that have been rendered deficient in at least two toxins chosen from PTX, DNT, AC and TCT. This patent discloses the over expression of an endogenous ampG gene by the addition of a strong promoter, and the addition of 11 terminal amino acids of the ampG gene from E. coli. 
Mielcarek et al, Vaccine (2006; 24S2: S2/54-S2-55) disclose a strain of Bordetella pertussis attenuated of PTX−, DTN− and TCT− for use in the immunization of mice. This reference discloses that to reduce the production of tracheal cytotoxin, the ampG gene should be overexpressed. However, upon further evaluation, the authors realized that by over-expressing the ampG gene, there is an increase in tracheal cytotoxin and not a decrease as was originally thought.
Mielcarek et al in Advance Drug Delivery Review 51 (2001) pgs. 55-69 disclose that live vaccines can induce systemic and mucosal responses when administered by the oral or nasal route.
Roduit et al in Infection and Immunity (2002 July; 70 (7): 3521-8) describe vaccinating neonatals and infants with mutated Bordetella strains with a DTP composition.
Mattoo et al, in Frontiers of Bioscience 6, e168-e186 (2001), suggest replacing the endogenous ampG gene in Bordetella with the E. coli ampG gene, which resulted in a decrease in the amount of TCT produced.
Thus, the prior art although disclosing various types of vaccinating compositions fails to address the problem of providing a vaccine or immunogenic composition that can provide protection to a newborn prior to six months. Furthermore, the prior art fails to disclose an immunogenic or a vaccine that provides rapid protective immunity against a Bordetella infection. The prior art also fails to disclose an immunogenic composition or vaccine that provides a rapid protective immunity against a Bordetella infection, said protective immunity increasing over at least the next two months following vaccination.
Therefore, it is an object of the present invention to overcome the deficiencies in the prior art.
It is another object of the present invention to produce a live attenuated vaccine candidate or immunogenic composition through genetic attenuation of a Bordetella strain such as B. pertussis or B. parapertussis to diminish pathogenicity, while maintaining the ability to colonize and induce protective immunity.
It is another object of the present invention to produce a vaccine or immunogenic composition that induces protection in newborns after a single intranasal administration that is superior to the protection provided by the current aPV.
It is yet another object of the present invention to provide protection against infection with Bordetella parapertussis, as well as Bordetella pertussis which was not seen after vaccination with aPV.
Another object of the present invention is to induce strong protective immunity in newborns against Bordetella infection.
Yet another object of the present invention is to provide a vaccine or immunogenic composition that induces mucosal and systemic immunity.
It is another object of the present invention to produce a live attenuated Bordetella pertussis strain to be given as a single-dose nasal vaccine in early life, called BPZE1.
It is yet another object of the present invention to provide a vaccine that can not only be used to vaccinate newborns, but can be used in all mammals of any age in the case of an epidemic of whooping cough.
Another object of the present invention is to provide a vaccine against Bordetella infection that induces a rapid protective immunity and/or a protective immunity that increases over at least the next two months after the vaccination.
Yet another object of the present invention is to provide prevention or treatment against Bordetella infection that is relatively low in production costs.
These and other objects are achieved by the present invention as evidenced by the summary of the invention, description of the preferred embodiments and the claims.